Gravity compensator applied to wearable muscular strength assisting apparatus

Abstract

A gravity compensator applied to a wearable muscular strength assisting apparatus includes a first link configured to extend parallel to a first body portion of a wearer, a second link configured to extend parallel to a second body portion and which is rotatably coupled to an end of the first link, an elastic body, which is fixed at an end thereof to the first link so as to exert an elastic force, which varies according to a length between the two ends thereof, and a connection unit, which is connected an end thereof to the other end of the elastic body and extends in a longitudinal direction of the first link and which is connected at an end thereof to the second link so as to vary a length of the elastic body by relative rotation between the first link and the second link.

What is claimed is: 
     
       1. A gravity compensator applied to a wearable muscular strength assisting apparatus, the gravity compensator comprising:
 a first link configured to extend in a direction parallel to a first body portion of a wearer; 
 a second link configured to extend in a direction parallel to a second body portion of the wearer, the second link being rotatably connected to a first side of the first body portion of the wearer and which is rotatably coupled to a first side of the first link; 
 an elastic body, having a first side fixed to the first link and an elastic force varying according to a change in length between the first side and a second side; and 
 a connection unit, having a first side connected to the second side of the elastic body, which extends along a longitudinal direction of the first link, and having a second side connected to the second link to vary the length of the elastic body by relative rotation of the first link and the second link, 
 wherein the connection unit includes: 
 a first rotator, which is fixed to the second link at a location, at which the first link is coupled to the second link, and which is rotatably secured to the first link; 
 a first wire, which is coupled at a first side thereof to the first rotator and extends in the longitudinal direction of the first link; 
 a second rotator, which is connected to a second side of the first wire and is rotatably coupled to the first link; and 
 a rotary link unit, which is fixed at a first side thereof to the second rotator and is coupled at a second side thereof to the second side of the elastic body so as to change the length of the elastic body and a direction in which the elastic force of the elastic body is exerted on the second rotator according to rotation of the second rotator. 
 
     
     
       2. The gravity compensator according to  claim 1 , further comprising a third wire which is rotatably secured at a first side thereof to a drive motor mounted on the first link and is connected at a second side thereof to the second link, wherein the first rotator includes:
 a first wire groove in which the first wire is received and engaged; and 
 a second wire groove, which is spaced apart from the first wire groove in a radial direction of the first rotator and in which the third wire is received. 
 
     
     
       3. The gravity compensator according to  claim 1 , wherein the rotary link unit includes:
 a first rotary link, which is rotatably secured at a first side thereof to the second rotator and is rotated therewith; and 
 a second rotary link, which is fixed at a first side thereof to the first link and is rotatably coupled at a second side thereof to a second side of the first rotary link, and wherein the second side of the elastic body is rotatably coupled to the first rotary link. 
 
     
     
       4. The gravity compensator according to  claim 1 , wherein the elastic body includes a plurality of elastic bodies, which are oriented in a direction perpendicular to the longitudinal direction of the first link, and wherein the gravity compensator further comprises an elastic-body link, which is coupled at a first side thereof to the second side of the elastic body and is rotatably coupled at a second side thereof to the first link. 
     
     
       5. The gravity compensator according to  claim 1 , wherein a torque, which is applied to the second link by elastic force of the elastic body, gradually increases and then decreases as the second link is rotated upwards with respect to the first link. 
     
     
       6. The gravity compensator according to  claim 5 , wherein the second link is rotatable in an up-and-down direction with respect to the first link, and is rotatable only between a first predetermined angle and a second predetermined angle, and
 wherein the torque applied to the second link is maximized at a third predetermined angle between the first predetermined angle and the second predetermined angle. 
 
     
     
       7. The gravity compensator according to  claim 5 , wherein the first body portion corresponds to the wearer's shoulder, and the second body portion corresponds to an upper arm rotatably connected to the wearer's shoulder. 
     
     
       8. The gravity compensator according to  claim 1 , wherein the connection unit includes a second wire, which is coupled at a first side thereof to the first rotator and extends in the longitudinal direction of the first link and which is connected to the second side of the elastic body so as to be moved by rotation of the first rotator. 
     
     
       9. The gravity compensator according to  claim 8 , wherein the connection unit includes a pulley, which is rotatably coupled to the second side of the elastic body and which is positioned between the first side and a second side of the second wire such that the second wire is wound around the pulley, and
 wherein the second side of the second wire extends in a reverse direction from a location at which the second wire is wound around the pulley, and is fixed to the first link. 
 
     
     
       10. The gravity compensator according to  claim 1 , wherein a torque, which is applied to the second link by elastic force of the elastic body, gradually increases as the second link is rotated upwards with respect to the first link. 
     
     
       11. The gravity compensator according to  claim 10 , wherein the first body portion corresponds to the wearer's upper arm, and the second body portion corresponds to a front arm rotatably connected to the wearer's upper arm.